(US politics, slang) Joe Biden, as the forty-sixth president of the United States.

(physics) A rare stable isotope of calcium, ⁴⁶₂₀Ca, having twenty protons and twenty-six neutrons; it amounts to only 0.004% of the element in nature

(physics) A minor stable isotope of titanium, ⁴⁶₂₂Ti, having twenty-two protons and twenty-four neutrons; it amounts to about 8% of the element in nature